A steering column is a device having a structure surrounding a steering shaft, which transfers rotational force generated according to the operation of a steering wheel performed by a driver to wheels of a vehicle, so as to support rotation of the steering shaft, and is assembled with a chassis of a vehicle through a mounting bracket so that the steering column fixes a position of a steering shaft.
The steering column includes a telescopic device and a tilt device, which can adjust the degree of protrusion and slant of the steering wheel to be suitable for the body shape of a driver.
FIG. 1a is a partially exposed perspective view of a conventional telescoping-tilting device of a steering column for a vehicle, and FIG. 1b is a sectional view of the telescoping-tilting device, which is assembled with a lever.
As shown in FIGS. 1a and 1b, the conventional telescoping-tilting device 100 of a steering column for a vehicle includes: a mounting bracket 107 for fixing a steering column to a chassis of a vehicle, the steering column including an inner tube 103 and an outer tube 105, which surround a steering shaft 101 in such a manner that they can slide respective to each other; a distance member 106 positioned within the mounting bracket 107 in such a manner that the distance member 106 is attached onto a part of an outer circumferential surface of the outer tube 105; and a lever 113 assembled with one side of the mounting bracket 107 through a bolt 109 and a cam 111.
The steering shaft 101 has an upper end connected with the steering wheel 102 and transfers rotational force generated according to the operation of the steering wheel 102 performed by the driver to wheels (not shown) of the vehicle, the wheels being positioned at a lower end of the steering shaft 101.
The inner tube 103 has a cylindrical shape having a uniform diameter and surrounds a lower part of the steering shaft 101. A lower bracket (not shown) is positioned on an outer circumferential surface of a lower part of the inner tube 103. Therefore, it is possible to fix a position of the inner tube 103 by fixing the lower bracket to the chassis of the vehicle.
The outer tube 105 has an inner diameter larger than an outer diameter of the inner tube 103 so that the outer tube 105 slides along the outer circumferential surface of the inner tube 103. That is, a telescoping operation can be performed. Meanwhile, the outer tube 105 surrounds an upper part of the steering shaft 101.
A distance member 106 is attached onto a part of the outer circumferential surface of the outer tube 105 by welding, etc. Each elongated hole (not shown) for adjusting the telescoping operation is formed at both sides of the distance member 106 in a direction parallel to the steering shaft. Also, a supporting member 119 for increasing strength can be installed at inner surfaces of both sides of the distance member 106.
The mounting bracket 107 is formed in such a manner that it surrounds the outer tube 105. The upper side of the mounting bracket is fixed in the chassis of the vehicle, and a supporting part 108, which is assembled with each outer surface of the both sides of the distance member 106, extends from the lower side of the mounting bracket. Also, an elongated hole 115 for adjusting a tilting operation is formed at the supporting part 108 in a direction perpendicular to the steering shaft so that a tilting operation of the steering column can be performed.
The lever 113 is assembled with a bolt 109 extending though the elongated hole 115 of the mounting bracket 107 and the elongated hole of the distance member 106, and the bolt 109 is assembled with a nut 118. As the lever 113 rotates around an axis of the bolt 109, a cam 111 disposed between the lever 113 and the supporting part 108 is driven so that each surface of the supporting part 108 of the mounting bracket 107 and each surface of the distance member 106, which face each other, make close contact with each other or are spaced from each other so as to set a locked state of the telescoping-tilting device 100 or a released state thereof.
However, in the conventional telescoping-tilting device 100 of a steering column for a vehicle, the mounting bracket 107 and the distance member 106 are fixed with each other while making close contact with each other by tightening force generated through the bolt 109, the nut 118 and the cam 111. Therefore, when external impact is transferred to the steering column because of collision of a vehicle, etc., the distance member 106 easily moves in an axial direction of the steering shaft within the mounting bracket 107. As a result, there is a problem in that a desired impact absorption mechanism cannot be achieved.